The present invention relates to a coating composition for rubber that imparts a coating having superior adhesion to rubber as well as superior wear resistance and surface lubricity.
A method for imparting lubricity and wear resistance to the surface of various types of rubbers has been used in the prior art in which, after applying a silicone resin composition to the surface of a rubber article, the composition is cured to form a cured coating layer to coat the surface of the rubber with the coating.
Examples of silicone resin compositions that have been proposed for use in this case include a composition comprising an organopolysiloxane containing epoxy groups and an alkoxysilane containing an amino group (see Japanese Patent Application Laid-open No. S54-43891), a composition comprising an organopolysiloxane containing hydroxyl groups, an organohydrogen polysiloxane, an organopolysiloxane containing epoxy groups and an alkoxysilane containing an amino group (see Japanese Patent Application Laid-open Nos. S54-45361, S54-90369 and S54-90375), a composition comprising an organopolysiloxane containing hydroxyl groups, an organohydrogen polysiloxane and the hydrolysis condensation product of a dialkoxysilane containing an amino group (see Japanese Patent Application Laid-open Nos. H7-109441 and H7-126417), a composition comprising an organopolysiloxane containing hydroxyl groups or vinyl groups, an organohydrogen polysiloxane and a dimethyl polysiloxane (see Japanese Patent Application Laid-open No. S62-215667), a composition comprising an organopolysiloxane containing a hydrolyzable group, an organopolysiloxane containing epoxy groups or amino groups and a hydrolyzable group and a hydrolyzable silane containing an epoxy group or an amino group (see Japanese Patent Application Laid-open No. H7-196984), a composition composed of a reaction product of a silane or siloxane containing an amino group and a silane or siloxane containing an epoxy group, a polydiorganosiloxane containing hydroxyl groups and a polyorganohydrogen siloxane (see Japanese Patent Application Laid-open No. S56-78960), a composition comprising a reaction product of a silane or siloxane containing an amino group and an alkoxy group and a silane or siloxane containing an epoxy group and an alkoxy group, and a polyorganosiloxane containing an alkoxy group or hydroxyl group and an amino group (see Japanese Patent Application Laid-open No. H11-43647), a composition comprising a polyorganosiloxane containing hydroxyl groups and epoxy groups, an alkoxysilane containing an amino group and an alkoxysilane containing a mercapto group (see Japanese Patent Application Laid-open No. H5-5082), a composition comprising a polydiorganopolysiloxane containing hydroxyl groups, a polyorganohydrogen siloxane, a organosiloxane containing a water-soluble amino group, an aminosilane compound, an epoxysilane compound, a carboxylic acid and an alkyl amine oxide (see Japanese Patent Application Laid-open No. 2002-188057), a composition composed of a hydrolysis condensation product of an acryl-silicone graft copolymer and an amino group-containing dialkoxysilane, and an organopolysiloxane containing epoxy groups (see Japanese Patent Application Laid-open No. H7-109440), and a composition composed of a diorganosiloxane containing hydroxyl groups, an epoxy resin and a silane containing a an amino group (see Japanese Patent Application Laid-open No. H4-318021).
However, since coatings obtained from these silicone resin compositions lack wear resistance and surface lubricity, silicone resin compositions blended with fine powder have been proposed to improve these properties.
Silicone resin compositions have been proposed which are blended with a fine powder such as polymethyl silsesquioxane, specific examples of which include a composition comprising a polyorganosiloxane containing hydroxyl groups, a polyorganosiloxane containing epoxy groups, an alkoxysilane containing an amino group and a polymethyl silsesquioxane powder (see Japanese Patent Application Laid-open No. S61-159427 and H2-233763), and a composition comprising a dimethyl polysiloxane containing a silanol group, a diorganopolysiloxane containing amino groups, a γ-glycidoxypropyl trimethoxysilane, and a polymethyl silsesquioxane fine powder (see Japanese Patent Application Laid-open No. H7-251124).
In addition, silicone resin compositions blended with a fine silicone rubber powder have also been proposed, examples of which include a composition comprising a non-flowable branched organopolysiloxane, a hydrolysis condensation product of a dialkoxysilane containing an epoxy group, a hydrolysis condensation product of a dialkoxysilane containing an amino group and a fine silicone rubber powder (see Japanese Patent Application Laid-open No. H7-233351), a composition comprising a non-flowable branched organopolysiloxane, a diorganopolysiloxane containing an amino group, a hydrolysis condensation product of a dialkoxysilane containing an epoxy group, a hydrolysis condensation product of a dialkoxysilane containing an amino group, a trialkoxysilane containing a (meth)acryloyl group or an amino group and a fine silicone rubber powder (see Japanese Patent Application Laid-open No. H7-310051), a composition comprising an organopolysiloxane, a hydrolysis condensation product of a dialkoxysilane containing an epoxy group, a hydrolysis condensation product of a dialkoxysilane containing an amino group and a fine silicone rubber powder (see Japanese Patent Application Laid-open No. H8-245882), a composition composed of an organopolysiloxane containing a hydroxyl group, a hydrolysis condensation product of a dialkoxysilane containing an epoxy group, a water-soluble amino compound and a fine silicone rubber powder (see Japanese Patent Application Laid-open No. H9-53047), and a composition comprising an organopolysiloxane containing an alkoxy group or a hydroxyl group, an organotrialkoxysilane, an organoalkoxysilane containing an amide group and a carboxyl group, an organoalkoxysilane containing an epoxy group and a silicone rubber fine powder (see Japanese Patent Application Laid-open No. H11-49955).
Silicone resin compositions blended with a polycarbonate resin fine powder have also been proposed, an example of which is a composition comprising an organopolysiloxane having alkenyl groups, an organohydrogen polysiloxane and a fine polycarbonate resin powder (see Japanese Patent Application Laid-open No. H9-12891).
In addition, silicone resin compositions blended with a fine polyethylene resin powder have also been proposed, an example of which is a composition comprising a curable silicone compoound and a fine polyethylene resin powder (see Japanese Patent Application Laid-open No. 2002-188056).